It is commonplace to produce various items, such as labels, tags, tickets and the like, by die cutting them from traveling web stock, using a roll having a cutting element of appropriate configuration on its outer surface. Holes and openings can of course be produced in such a manner, but serious problems may arise as a result of the accumulation of scrap material within the die element; such accumulations will quickly render the roll ineffective, and may cause severe damage, such as bursting of the dies.
In an effort to avoid such problems, it is now quite common to employ hollow die-cutting rolls having channels extending between the cavity and the surface thereof within the confines of the cutting elements, with air charged into the roll cavity serving to eject the lodged pieces of scrap. Such air-eject rolls are disclosed, for example, in the following U.S. Pat. Nos. 3,698,271 and 3,698,272 to Kesten et al, 3,766,814 to Kesten, and 4,191,077 to Edwards et al., each of common assignment herewith. Although effective for their intended purposes, devices of the sort shown in these patents discharge the cut material outwardly, which may in certain instances entail less than optimal scrap management practices.
It has also been proposed to handle chips, slugs, confetti and the like, cut from web stock by rotary die cutting devices, by withdrawing the fragments into the cutting roll under vacuum, for direct discharge to a suitable container. Such systems are disclosed, for example, in U.S. Pat. Nos. 3,174,428 to Huck; 3,194,095 to Buck et al; 3,602,080 to Sickel; 3,680,419 to Stoop; and 4,037,501 to Gladow. Other U.S. Pat. Nos. of possible interest include the following:
Copland No. 705,040 discloses the use of vacuum and positive pressure for managing dough on a rotary cutting cylinder, and uses brushes to clean the surface of the die. A similar arrangement, for handling rubberized fabric strips, is shown is U.S. Pat. No. 1,825,250 to Rehak.
In Remde et al U.S. Pat. No. 3,872,752, apparatus is disclosed for cutting snack food dough, which uses a vacuum holding feature and also has positive pressure means for stripping purposes. Vacuum may be applied through passages which have a first zone parallel to the axis of the waste-removal drum in which they are contained, communicating with enlarged portions on the surface through several radially extending sections.
Koppa et al U.S. Pat. No. 4,276,800 describes a cutter for scoring dough sheets, and discloses a system using both vacuum and positive pressure, and employing multiple ports. Other forms of vacuum die rolls are shown in Stemmler U.S. Pat. Nos. 3,380,327 and Feick et al 3,404,607.
Despite the foregoing developments, a need remains for rotary die cutting apparatus which is effective for producing holes and other shapes in traveling web materials, which also functions to remove and dispose of the waste in an optimal, clean and efficient manner.
Accordingly, it is a primary object of the present invention to provide a novel rotary device, and a novel assembly utilizing the same, for cutting holes and other shapes in web materials, and for clearing the waste therefrom, which device operates at high speeds and produces a minimal amount of contamination.
It is also an object of the invention to provide such a device in which the effectiveness of scrap removal is such as to significantly reduce or virtually eliminate down-time required for cleaning material from the scrap exit path.
Another object of the invention is to provide a novel punching die insert adapted for mounting upon the exterior surface of a die cutting roll, and providing a secondary air-flow assist feature for promoting movement of scrap through associated channels of the roll body.